Strength and deformation characteristics of irregular columnar jointed rock mass: A combined experimental and theoretical study

The irregularity of jointed network poses a challenge to the determination of field mechanical param-eters of columnar jointed rock mass(CJRM),and a reasonable prediction of deformation and strength characteristics of CJRM is important for engineering construction.The Voronoi diagram and three-dimensional printing technology were used to make an irregular columnar jointed mold,and the irregular CJRM(ICJRM)specimens with different dip directions and dip angles were prepared.Uniaxial compression tests were performed,and the anisotropic strength and deformation characteristics of ICJRM were described.The failure modes and mechanisms were revealed in accordance with the final appearances of the ICJRM specimens.Based on the model test results,the empirical correlations for determining the field deformation and strength parameters of CJRM were derived using the dip angle and modified joint factor.The proposed empirical equations were used in the Baihetan Project,and the calculated mechanical parameters were compared with the field test results and those obtained from the tunneling quality index method.Results showed that the deformation parameters determined by the two proposed methods are all consistent with the field test results,and these two methods can also estimate the strength parameters effectively.

Fracture behaviors of columnar jointed rock mass using interface mechanics theorem

For a special geological structure of columnar jointed rock mass(CJRM),its mechanical properties are strongly affected by the columnar joints.To describe the fracture behaviors of CJRM using the basic theories of interface mechanics for composite materials,the interface stresses of the vertical and horizontal joints,which are the two primary joints in the CJRM under triaxial compression,are studied,and their mathematical expressions are derived based on the superposition principle.Based on the obtained interface stresses of the vertical and horizontal joints in the CJRM,the crack initiation of the joint interface in the CJRM is studied using the maximum circumferential stress theory in fracture mechanics.Moreover,based on this investigation,the fracture behaviors of CJRM are analyzed.According to the results of similar material physical model tests for the CJRM,the theoretical study is verified.Finally,the influence of the mechanical parameters of the CJRM on the joint interface stress is discussed comprehensively.

Predictive factors and model validation of post-colon polyp surgery Helicobacter pylori infection

BACKGROUND Recently,research has linked Helicobacter pylori(H.pylori)stomach infection to colonic inflammation,mediated by toxin production,potentially impacting colorectal cancer occurrence.AIM To investigate the risk factors for post-colon polyp surgery,H.pylori infection,and its correlation with pathologic type.METHODS Eighty patients who underwent colon polypectomy in our hospital between January 2019 and January 2023 were retrospectively chosen.They were then randomly split into modeling(n=56)and model validation(n=24)sets using R.The modeling cohort was divided into an H.pylori-infected group(n=37)and an H.pylori-uninfected group(n=19).Binary logistic regression analysis was used to analyze the factors influencing the occurrence of H.pylori infection after colon polyp surgery.A roadmap prediction model was established and validated.Finally,the correlation between the different pathological types of colon polyps and the occurrence of H.pylori infection was analyzed after colon polyp surgery.RESULTS Univariate results showed that age,body mass index(BMI),literacy,alcohol consumption,polyp pathology type,high-risk adenomas,and heavy diet were all influential factors in the development of H.pylori infection after intestinal polypectomy.Binary multifactorial logistic regression analysis showed that age,BMI,and type of polyp pathology were independent predictors of the occurrence of H.pylori infection after intestinal polypectomy.The area under the receiver operating characteristic curve was 0.969[95%confidence interval(95%CI):0.928–1.000]and 0.898(95%CI:0.773–1.000)in the modeling and validation sets,respectively.The slope of the calibration curve of the graph was close to 1,and the goodness-of-fit test was P>0.05 in the two sets.The decision analysis curve showed a high rate of return in both sets.The results of the correlation analysis between different pathological types and the occurrence of H.pylori infection after colon polyp surgery showed that hyperplastic polyps,inflammatory polyps,and the occurrence of H.pylori infection were not significantly correlated.In contrast,adenomatous polyps showed a significant positive correlation with the occurrence of H.pylori infection.CONCLUSION Age,BMI,and polyps of the adenomatous type were independent predictors of H.pylori infection after intestinal polypectomy.Moreover,the further constructed column-line graph prediction model of H.pylori infection after intestinal polypectomy showed good predictive ability.

Predictive value of NLR, Fib4, and APRI in the occurrence of liver failure after hepatectomy in patients with hepatocellular carcinoma

BACKGROUND Neutrophil-lymphocyte ratio(NLR),fibrosis index based on four factors(Fib4),aspartate aminotransferase-to-platelet ratio index(APRI)can be used for prognostic evaluation of hepatocellular carcinoma.However,no study has established an individualized prediction model for the prognosis of hepatocellular carcinoma based on these factors.AIM To screen the factors that affect the prognosis of hepatocellular carcinoma and establish a nomogram model that predicts postoperative liver failure after hepatic resection in patients with hepatocellular carcinoma.METHODS In total,220 patients with hepatocellular carcinoma treated in our hospital from January 2022 to January 2023 were selected.They were divided into 154 participants in the modeling cohort,and 66 in the validation cohort.Comparative analysis of the changes in NLR,Fib4,and APRI levels in 154 patients with hepatocellular carcinoma before liver resection and at 3 mo,6 mo,and 12 mo postoperatively was conducted.Binary logistic regression to analyze the influencing factors on the occurrence of liver failure in hepatocellular carcinoma patients,roadmap prediction modeling,and validation,patient work characteristic curves(ROCs)to evaluate the predictive efficacy of the model,calibration curves to assess the consistency,and decision curve analysis(DCA)to evaluate the model’s validity were also conducted.RESULTS Binary logistic regression showed that Child-Pugh grading,Surgical site,NLR,Fib4,and APRI were all risk factors for liver failure after hepatic resection in patients with hepatocellular carcinoma.The modeling cohort built a column-line graph model,and the area under the ROC curve was 0.986[95%confidence in terval(CI):0.963-1.000].The patients in the validation cohort utilized the column-line graph to predict the probability of survival in the validation cohort and plotted the ROC curve with an area under the curve of the model of 0.692(95%CI:0.548-0.837).The deviation of the actual outcome curves from the calibration curves of the column-line plots generated by the modeling and validation cohorts was small,and the DCA confirmed the validity.CONCLUSION NLR,Fib4,and APRI independently influence posthepatectomy liver failure in patients with hepatocellular carcinoma.The column-line graph prediction model exhibited strong prognostic capability,with substantial concordance between predicted and actual events.

The Late Carboniferous–Early Permian Ocean-Continent Transition in the West Junggar,Central Asian Orogenic Belt: Constraints from Columnar Jointed Rhyolite

The West Junggar of the western Central Asian Orogenic Belt is one of the typical regions in the term of ocean subduction, contraction and continental growth in the Late Paleozoic. However, it is still controversial on the exact time of ocean-continent transition so far. This study investigates rhyolites with columnar joint in the West Junggar for the first time.Based on zircon U-Pb dating, we determined that the ages of the newly-discovered rhyolites are between 303.6 and 294.5 Ma, belonging to Late Carboniferous–Early Permian, which is the oldest rhyolite with columnar joint preserved in the world at present. Geochemical results show that the characteristics of the major element compositions include a high content of SiO_2(75.78–79.20 wt%) and a moderate content of Al_2O_3(12.21–13.19 wt%). The total alkali content(K_2O +Na_2O) is 6.14–8.05 wt%, among which K_2O is 2.09–4.72 wt% and the rate of K_2O/Na_2O is 0.38–3.05. Over-based minerals such as Ne, Lc, and Ac do not appear. The contents of TiO_2(0.09–0.24 wt%), CaO(0.15–0.99 wt%) and MgO(0.06–0.18 wt%) are low. A/CNK=0.91–1.68, A/NK=1.06–1.76, and as such, these are associated with the quasi-aluminum-weak peraluminous high potassium calc-alkaline and some calc-alkaline magma series. These rhyolites show a significant negative Eu anomaly with relative enrichment of LREE and LILE(Rb, Ba, Th, U, K) and depletion of Sr, HREE and HFSE(Nb, Ta, Ti, P). These rhyolites also have the characteristics of an A2-type granite, similar to the Miaoergou batholith,which indicates they both were affected by post-orogenic extension. Combining petrological, zircon U-Pb dating and geochemical characteristics of the rhyolites, we conclude that the specific time of ocean-continent transition of the West Junggar is the Late Carboniferous–Early Permian.

Mechanism of reduction of columnar dendrite spacing in unidirectional solidification caused by electric current passing through solid liquid interface

Considering the S L interface morphology stability, the S L interface energy, the Joule heat produced by electric current at the S L interface, and the change of solute concentration at the S L interface indirectly caused by electric current, the mechanism of reduction of columnar dendrite spacing in unidirectional solidification caused by electric current passing through solid liquid interface was studied. The following conclusions can be drawn that: 1) under sub rapid solidification condition, increasing electric current density will improve the stability of S L interface, thus decreasing the columnar dendrite spacing; 2)there are two ways by which the increase of electric current decreases the columnar dendrite spacing, one is promoting the splitting of the protruding tips at the S L interface, the other is promoting the forming of new convex parts at the bottom of the concave interface.[

High Potential Columnar Nanocrystalline AlN Films Deposited by RF Reactive Magnetron Sputtering

Columnar nanocrystalline aluminum nitride(cnc-AlN) thin films with(002) orientation and uniform texture have been deposited successfully on large silicon wafers by RF reactive magnetron sputtering.At the optimum sputtering parameters, the deposited cnc-AlN thin films show a c-axis preferred orientation with a crystallite size of about 28 nm and surface roughness(RMS) of about 1.29 nm. The cnc-AlN thin films were well transparent with an optical band gap about 4.8 e V, and the residual compressive stress and the defect density in the film have been revealed by Ramon spectroscopy. Moreover, piezoelectric performances of the cnc-AlN thin films executed effectively in a film bulk acoustic resonator structure.

Unloading performances and stabilizing practices for columnar jointed basalt:A case study of Baihetan hydropower station

The columnar jointed rock mass(CJR), composed of polygonal cross-sectional columns cut by several groups of joints in various directions, was exposed during the excavations of the Baihetan hydropower station, China. In order to investigate the unloading performances and the stability conditions during excavation of the columns, an experimental field study was performed. Firstly, on-site investigations indicated that the geotechnical problems, including rock relaxation, cracking and collapse, were the most prominent for the CJR Class I that contains intensive joint network and the smallest column sizes.Comprehensive field tests, including deformation measurement by multi-point extensometers, ultrasonic wave testing, borehole television observation and stress monitoring of rock anchors, revealed that the time-dependent relaxation of the CJRs was marked. The practical excavation experiences for the Baihetan columnar jointed rock masses, such as blasting scheme, supporting time of shotcrete and rock bolts, were presented in the excavations of the diversion tunnels. These detailed investigations and practical construction experiences can provide helpful information for similar geotechnical works in jointed rock mass.

Effect of titanium content on the refinement of coarse columnar austenite grains during the solidification of peritectic steel

The effect of titanium content on the refinement of austenite grain size in as-cast peritectic carbon steel was investigated by fast directional solidification experiments with simulating the solidification and growth of surface and subsurface austenite in continuously cast slabs.Transmission electron microscope(TEM)and scanning electron microscope(SEM)were used to analyze the size and distribution of Ti(C,N)precipitates during solidification.Based on these results,the pinning pressure of Ti(C,N)precipitates on the growth of coarse columnar grains(CCGs)was studied.The results show that the austenite microstructure of as-cast peritectic carbon steel is mainly composed of the regions of CCGs and fine columnar grains(FCGs).Increasing the content of titanium reduces the region and the short axis of the CCGs.When the content of titanium is 0.09wt%,there is no CCG region.Dispersed microscale particles will firstly form in the liquid,which will decrease the transition temperature from FCGs to CCGs.The chain-like nanoscale Ti(C,N)will precipitate with the decrease of the transition temperature.Furthermore,calculations shows that the refinement of the CCGs is caused by the pinning effect of Ti(C,N)precipitates.

Methylation of DAPK and THBS1 genes in esophageal gastric-type columnar metaplasia

AIM: To explore methylation of DAPK, THBS1, CDH-1, and p14 genes, and Helicobacter pylori(H. pylori) status in individuals harboring esophageal columnar metaplasia.METHODS: Distal esophageal mucosal samples obtained by endoscopy and histologically diagnosed as gastric-type(non-specialized) columnar metaplasia, were studied thoroughly. DNA was extracted from paraffin blocks, and methylation status of deathassociated protein kinase(DAPK), thrombospondin-1(THBS1), cadherin-1(CDH1), and p14 genes, was examined using a methyl-sensitive polymerase chain reaction(MS-PCR) and sodium bisulfite modification protocol. H. pylori cag A status was determined by PCR.RESULTS: In total, 68 subjects(33 females and 35 males), with a mean age of 52 years, were included. H. pylori cag A positive was present in the esophageal gastric-type metaplastic mucosa of 18 individuals. DAPK, THSB1, CDH1, and p14 gene promoters were methylated by MS-PCR in 40(58.8%), 33(48.5%), 46(67.6%), and 23(33.8%) cases of the 68 esophageal samples. H. pyloristatus was associated with methylation of DAPK(P = 0.003) and THBS1(P = 0.019).CONCLUSION: DNA methylation occurs in cases of gastric-type(non-specialized) columnar metaplasia of the esophagus, and this modification is associated with H. pylori cag A positive infection.

Immunogenicity and protective role of antigenic regions from five outer membrane proteins of Flavobacterium columnare in grass carp Ctenopharyngodon idella

Flavobacterium columnare causes columnaris disease in freshwater fi sh. In the present study, the antigenic regions of fi ve outer membrane proteins(OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 k Da, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purifi ed recombinant protein was used to vaccinate the grass carp, C tenopharyngodon idella. Following vaccination of the fi sh their Ig M antibody levels were examined, as was the expression of I g M, Ig D and Ig Z immunoglobulin genes and other genes such as MHC Iα and MHC I I β, which are also involved in adaptive immunity. Interleukin genes( IL), including I L- 1β, IL- 8 and I L- 10, and type I and type II interferon(I FN) genes were also examined. At 3 and 4 weeks post-vaccination(wpv), signifi cant increases in Ig M antibody levels were observed in the fi sh vaccinated with the recombinant fusion protein, and an increase in the expression levels of I g M, Ig D and Ig Z genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fi sh. At four wpv, the fi sh were challenged with F. column a re, and the vaccinated fi sh showed a good level of protection against this pathogen, with 39% relative percent survival(RPS) compared with the control group. It can be concluded, therefore, that the fi ve OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fi sh and protection against F. columnare.

Feasibility of columnar jointed basalt used for high-arch dam foundation

Columnar jointed basalt, with a lot of small-spacing structural planes and poor integrity, is a kind of fractured rock mass. Through comprehensive study of columnar joints shape, roughness of fracture surface and chemical composition of basalt, it is known that columnar joints of Baihetan dam area were formed as a result of cooling and shrinkage effects of magma. The columnar jointed basalt is mainly formed through chemical reaction of chlorite, kaolinite, epidote and tremolite, and the columnar joints mainly consist of chlorite according to slice identification and chemical analysis. Test results show that the columnar jointed basalt has high uniaxial compressive strength, low friction coefficient, and high cohesion, shear strength and deformation index. Meanwhile, the columnar jointed basalt is closely locked, and joint surfaces are well closed. The permeability of the rock is quite weak, and the P-wave velocity in the rock could get up to 5 000 m/s. All these show good rock properties. The columnar joints develop regularly, different from the general fractured rock masses. In summary, the columnar jointed basalt can be used directly as a foundation of dam.

Phase field simulation of the columnar dendritic growth and microsegregation in a binary alloy

This paper applies a phase field model for polycrystalline solidification in binary alloys to simulate the formation and growth of the columnar dendritic array under the isothermal and constant cooling conditions. The solidification process and microsegregation in the mushy zone are analysed in detail. It is shown that under the isothermal condition solidification will stop after the formation of the mushy zone, but dendritic coarsening will progress continuously, which results in the decrease of the total interface area. Under the constant cooling condition the mushy zone will solidify and coarsen simultaneously. For the constant cooling solidification, microsegregation predicted by a modified Brody- Flemings model is compared with the simulation results. It is found that the Fourier number which characterizes microsegregation is different for regions with different microstructures. Dendritic coarsening and the larger area of interface should account for the enhanced Fourier number in the region with well developed second dendritic arms.

Effects of Thickness on the Electrical Conductivity of Sputtered YSZ Film with Nanocrystalline Columnar Microstructure

In order to investigate the effect of the thickness on the electrical conductivity of yttriastabilized zirconia(YSZ) film, the nanocrystalline columnar-structured YSZ film with thickness of 0.67-2.52 μm was prepared by magnetron sputtering through controlling the deposition time. All the sputtered films with different thicknesses consist of the main phase of cubic YSZ as well as a small amount of monoclinic YSZ. The thicker films exhibit a typical columnar grain structure based on the fractured cross-sectional SEM observations. The average diameters of columnar grains increase from about 40 nm to 100 nm with the film thickness from 0.67 μm to 2.52 μm according to TEM analysis. The thinnest YSZ film with 0.67 μm thickness shows the highest apparent electrical conductivity in the four films in 400-800 ℃ due to the contribution from the highly conductive film/substrate interfacial region. On the other hand, the real electrical conductivities of YSZ films increase with film thickness from 0.67 μm to 2.52 μm after eliminating the contribution of the film/substrate interface. The increasing film thickness leads to the grain growth as well as the decrement in the volumetric fraction of the resistive columnar grain boundary and a consequent higher real electrical conductivity.

Urinary and sexual function changes in benign prostatic hyperplasia patients before and after transurethral columnar balloon dilatation of the prostate

BACKGROUND Transurethral columnar balloon dilatation of the prostate(TUCBDP) is a new surgical treatment, but its efficacy remains controversial because of limited clinical application.AIM To investigate the clinical effect of TUCBDP for benign prostatic hyperplasia(BPH).METHODS Overall, 140 patients with BPH who underwent surgical treatment were included in the study. A random number table was used to divide the participants into study and control groups(n = 70 per group). The study group underwent TUCBDP. The prostate resection surgical time, intraoperative blood loss, bladder irrigation time, catheter indwelling time, length of hospital stay, International Prostate Symptom Score(IPSS), maximum urine flow rate(Qmax), residual urine volume(RUV), changes in the International Erectile Function Score(ⅡEF-5) score, serum prostate-specific antigen(PSA), quality of life(QOL) score, and surgical complications were compared in both groups.RESULTS The operation time, intraoperative blood loss volume, bladder flushing time, urinary catheter indwelling time, and length of hospital stay were significantly lower in the study group than in the control group(P < 0.05). There were no significant differences in the IPSS, Qmax, and RUV measurements between the study and control groups(P > 0.05). However, at 3 mo post-surgery, the IPSS and RUV measurements were both lower(P < 0.05) and Qmax values were higher(P < 0.05) compared to the pre-surgery results in both groups. The ⅡEF-5 scores before and 3 mo after surgery were not significantly different between the study and control groups(P > 0.05). At 1 mo after surgery, the ⅡEF-5 score was higher in the study group than in the control group(P < 0.05). The serum PSA levels and QOL scores before treatment and at 1 and 3 mo after treatment were not significantly different between the study and control groups(P > 0.05). However, lower serum PSA levels and QOL scores were observed after 1 and 3 mo of treatment compared to pre-treatment levels in the study group(P < 0.05). The surgical complication rate of the study group(4.29%) was lower than that of the control group(12.86%;P < 0.05).CONCLUSION TUCBDP for BPH and transurethral resection of the prostate can achieve better results, but the former method is associated with less surgical trauma.

Effect of compression direction on the dynamic recrystallization behavior of continuous columnar-grained CuNi10Fe1Mn alloy

The dynamic recrystallization（DRX） behavior of continuous columnar-grained（CCG） Cu Ni10Fe1 Mn alloy was investigated by hot compression along the solidification direction（SD） and perpendicular to the solidification direction（PD）. Specimens were compressed to a true strain of 0.8 at temperatures ranging from 25°C to 900°C and strain rates ranging from 0.01 to 10 s-1. The results indicate that DRX nucleation at grain boundaries（GBs） and DRX nucleation at slip bands（SBs） are the two main nucleation modes. For SD specimens, C-shaped bending and zig-zagging of the GBs occurred during hot compression, which made DRX nucleation at the GBs easier than that at the SBs. When ln Z ≤ 37.4（Z is the Zener–Hollomon parameter）, DRX can occur in SD specimens with a critical temperature for the DRX onset of;50°C and a thermal activated energy（Q） of 313.5 k J·mol-1. In contrast, in PD specimens, the GBs remained straight, and DRX nucleation occurred preferentially at the SBs. For PD specimens, the critical temperature is about 700°C, Q is 351.7 k J·mol-1, and the occurrence condition of DRX is ln Z ≤ 40.1. The zig-zagging of GB morphology can significantly reduce the nucleation energy at the GBs; as a result, DRX nucleation occurs more easily in SD specimens than in PD specimens.

Hot deformation characteristics of as-cast high-Cr ultra-super-critical rotor steel with columnar grains

Isothermal hot compression tests of as-cast high-Cr ultra-super-critical（USC） rotor steel with columnar grains perpendicular to the compression direction were carried out in the temperature range from 950 to 1250°C at strain rates ranging from 0.001 to 1 s^（-1）. The softening mechanism was dynamic recovery（DRV） at 950°C and the strain rate of 1 s^（-1）, whereas it was dynamic recrystallization（DRX） under the other conditions. A modified constitutive equation based on the Arrhenius model with strain compensation reasonably predicted the flow stress under various deformation conditions, and the activation energy was calculated to be 643.92 kJ ×mol^（-1）. The critical stresses of dynamic recrystallization under different conditions were determined from the work-hardening rate（θ）–flow stress（σ） and-θ/σ–σ curves. The optimum processing parameters via analysis of the processing map and the softening mechanism were determined to be a deformation temperature range from 1100 to 1200°C and a strain-rate range from 0.001 to 0.08 s^（-1）, with a power dissipation efficiency η greater than 31%.

Effects of aging treatment on the microstructure and superelasticity of columnar-grained Cu71Al18Mn11 shape memory alloy

The effect of aging treatment on the superelasticity and martensitic transformation critical stress in columnar-grained Cu_（71）Al_（18）Mn_（11） shape memory alloy（SMA） at the temperature ranging from 250°C to 400°C was investigated. The microstructure evolution during the aging treatment was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results show that the plate-like bainite precipitates distribute homogeneously within austenitic grains and at grain boundaries. The volume fraction of bainite increases with the increase in aging temperature and aging time, which substantially improves the martensitic transformation critical stress of the alloy, whereas the bainite only slightly affects the superelasticity. This behavior is attributed to a coherent relationship between the bainite and the austenite, as well as to the bainite and the martensite exhibiting the same crystal structure. The variations of the martensitic transformation critical stress and the superelasticity of columnar-grained Cu_（71）Al_（18）Mn_（11） SMA with aging-temperature and aging time are described by the Austin-Rickett equation, where the activation energy of bainite precipitation is 77.2 kJ ·mol1. Finally, a columnar-grained Cu_（71）Al_（18）Mn_（11） SMA with both excellent superelasticity（5%-9%） and high martensitic transformation critical stress（443-677 MPa） is obtained through the application of the appropriate aging treatments.

Signatures of a Universal Spectrum for Nonlinear Variability in Daily Columnar Total Ozone Content

Continuous periodogram analyses of sets of 50 to 364 daily mean atmospheric columnar total ozone content at19 globally representative stations indicate that the power spectra fOllow the universal inverse power law form of thestatistical normal distribution. The results are consistent with prediction of a cell dynamical system model for atmospheric flows extending up to the stratosphere and above. The unique quantification for nonlinear variability of dailyatmospheric total ozone implies predictability of the total pattern of fluctuations.